Power circuit simplifies USB battery charger design

Texas Instruments Incorporated introduced what is said to be the industry's smallest 1.1-A Li-Ion linear battery charger with integrated 50-mA low-dropout regulator to support mobile phones and other handheld electronics. The new bq25040 comes in a small 2 mm x 3 mm package, and can regulate voltage within one-percent accuracy from a USB port or AC adapter. The device's integrated LDO allows a mobile application to power up instantly from an external power source, even with an empty or absent battery.

The bq25040 also saves manufacturing time and cost by eliminating the need for battery setup during production test phase. The charger's single-input interface selects the appropriate charge current and places the device into production test mode.

1. 30V input with overvoltage protection enables safe charging with unregulated or aftermarket adapters
2. Up to 1.1-A charge rate
3. Integrated 50-mA LDO supplies power to external circuits, such as a USB transceiver
4. Production test mode regulates 4.2-V output without battery connection, and supplies up to 2.3 A
5. Selectable 100-mA or 500-mA USB current limit complies with USB standards
6. Input voltage dynamic power management provides protection against poor USB sources

The bq25040 is available now in a 10-pin, QFN package and is priced at $1.20 in quantities of 1,000. Other USB chargers include the bq24150 ultra-small switch-mode charger with integrated FETs, and the bq24072 with dynamic power path management.